Studies were conducted to examine the effect of the interaction between glucose and amino acids in regulating insulin mediated protein turnover in vivo. Subjects were studies after an overnight fast and were subjected to a hyperinsulinemic suglycemic or hyperinsulinemic hyperglycemic clamps in the presence and absence of amino acids. Availability of amino acids enhance the suppressive effect of insulin on protein breakdown and additionally the presence of hyperglycemia stimulates the rate of proteolysis in vivo.